Prediction and optimization of process parameter of friction stir welded AA5083-H111 aluminum alloy using response surface methodology

A systematic approach was presented to develop the empirical model for predicting the ultimate tensile strength of AA5083-H111 aluminum alloy which is widely used in ship building industry by incorporating friction stir welding(FSW) process parameters such as tool rotational speed,welding speed,and axial force.FSW was carried out considering three-factor five-level central composite rotatable design with full replications technique.Response surface methodology(RSM) was applied to developing linear regression model for establishing the relationship between the FSW process parameters and ultimate tensile strength.Analysis of variance(ANOVA) technique was used to check the adequacy of the developed model.The FSW process parameters were also optimized using response surface methodology(RSM) to maximize the ultimate tensile strength.The joint welded at a tool rotational speed of 1 000 r/min,a welding speed of 69 mm/min and an axial force of 1.33 t exhibits higher tensile strength compared with other joints.

Optimization of fermentation conditions for 1,3-propanediol production by marine Klebsiella pneumonia HSL4 using response surface methodology

The industrially important organic compound 1,3-propanediol （1,3-PDO） is mainly used as a building block for the production of various polymers. In the present study, response surface methodology protocol was followed to determine and optimize fermentation conditions for the maximum production of 1,3-PDO using marine-derived Klebsiella pneumoniae HSL4. Four nutritional supplements together with three independent culture conditions were optimized as follows： 29.3 g/L glycerol, 8.0 g/L K2HPO4, 7.6 g/L （NH4）2SO4, 3.0 g/L KH2PO4, pH 7.1, cultivation at 35℃ for 12 h. Under the optimal conditions, a maximum 1,3-PDO concentration of 14.5 g/L, a productivity of 1.21 g/（L＇h） and a conversion of glycerol of 0.49 g/g were obtained. In comparison with the control conditions, fermentation under the optimized conditions achieved an increase of 38.8% in 1,3-PDO concentration, 39.0% in productivity and 25.7% in glycerol conversion in flask. This enhancement trend was further confirmed when the fermentation was conducted in a 5-L fermentor. The optimized fermentation conditions could be an important basis for developing low- cost, large-scale methods for industrial production of 1,3-PDO in the future.

Establishment of Hypoglycemic Agent Screening Method Based on Human Glucokinase

Objective To establish a reliable platform for screening glucokinase activators （GKAs） in vitro. Methods Pancreatic glucokinase （PGK） protein expressed in a prokaryotic expression system as a histidine-tagged fusion protein from Homo sapiens was produced. Then, response surface methodology （RSM） was used to optimize the microplate-based GKA screening platform. In the f＇trst step of optimization with Plackett-Burman design （PBD）, initial pH, reaction time and MgC12 were found to be important factors affecting the activity ratio of GKA （RO-28-1675） significantly. In the second step, a 23 full factorial central composite design （CCD） and RSM were applied to the optimal condition determination of each significant variable. A second-order polynomial was determined by a multiple regression analysis of the experimental data. Results The following optimal values for the critical factors were obtained： initial pH 0 （7.0）, reaction time-0.63 （13.7 min） and MgC12 0.11 （2.11 mmol/L） with a predicted value of the maximum activity ratio of 34.1%. Conclusion Under the optimal conditions, the practical activity ratio is 34.8%. The determination coefficient （R2） is 0.9442, ensuring adequate credibility of the model. LLAE3, extracted from Folium nelumbinis in our laboratory, has prominently activated effects on PGK.

Box-Behnken experimental design for optimizing process parameters in carbonate-promoted direct thiophene carboxylation reaction with carbon dioxide

A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten state.The effects of reaction factors on the carboxylate yield are investigated in the preliminary screening experiments,and the phase behavior analysis of the reaction medium is detected through the thermal characterization analysis of insitu high temperature X-ray diffraction measurement(in-situ XRD).The application of response surface methodology(RSM)based on the Box-Behnken design(BBD)is conducted to investigate the effect of the reaction parameters,such as reaction temperatu re,carbonate proportion,CO_(2) pressure and thiophene amount,on the product yield.The regressed second-order polynomial model equation well correlates all the independent variables.The analysis of variance(ANOVA)results reveal that the quadratic effect of reaction temperature is the most effective parameter in this carboxylation reaction owing to it’s the highest contribution to the sum of square(30.18%).The optimum reaction conditions for maximum product yield are the reaction temperature of 287℃,carbonate proportion of 32.20%,CO_(2) pressure of 1.0MPa and thiophene amount of 9.35 mmol.Operating under these selected experimental conditions,a high product yield(50.98%)can be achieved.

Parameter Identification Based on Force-Displacement Curves for a Bolted Joint Finite Element Model

In order to identify the uncertain parameters of a bolted joint finite element model,a simple and applicable way of parameter identification is introduced.By utilizing numerical simulation with the Abaqus software and experimental investigation with the MTS material testing system,the tangential force-displacement curves that reflect the characteristics of the bolted joint were acquired.On the basis of this,by employing the response surface methodology（RSM）and genetic algorithms（GAs）,parameters in the FEM model were identified.The force-displacement curves by both virtual and experimental approaches are well correlated at the end.This phenomenon-based parameter identification method may help facilitate precise prediction of complex jointed connection structures.

Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force （Fz） and surface roughness （Ra）. In the present work, the performance of PVD/TiA1N coated carbide inserts was investigated using response surface methodology （RSM） for turning Ti-6A1-4V. The effects of process parameters such as speed （v）, feed （/＇）, depth of cut （d） and back rake angle （Ty） on Fz and Ra were investi- gated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design （CCD）. The experimental results indi- cated that Fz increased with the increase in d, f and decreased with the increase in v and yy, whereas Ra decreased with the increase in v and 7y, and increased with d and v. The goodness of fit of the regression equations and model fits （R2） for Fz and Ra were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.

Optimization of endwall contouring in axial compressor S-shaped ducts

This paper presents a numerical investigation of the potential aerodynamic benefits of using endwall contouring in a fairly aggressive duct with six struts based on the platform for endwall design optimization.The platform is constructed by integrating adaptive genetic algorithm（AGA）, design of experiments（DOE）, response surface methodology（RSM） based on the artificial neural network（ANN）, and a 3D Navier–Stokes solver.The visual analysis method based on DOE is used to define the design space and analyze the impact of the design parameters on the target function（response）.Optimization of the axisymmetric and the non-axisymmetric endwall contouring in an S-shaped duct is performed and evaluated to minimize the total pressure loss.The optimal ducts are found to reduce the hub corner separation and suppress the migration of the low momentum fluid.The non-axisymmetric endwall contouring is shown to remove the separation completely and reduce the net duct loss by 32.7%.